Examples of a drip bag by which one cup of coffee can be easily made by a typical paper drip method include a drip bag in which coffee powder is packed in a bag body formed from a water permeable filterable sheet, and a holder is adhered to the side of the bag body. Although this drip bag may have various configurations, examples of a drip bag suitable for industrial production include a drip bag wherein concave portions for hooking the drip bag on the cup are formed on both the right and left ends of a sheet-shaped paper member, which serves as a holder by folding it into right and left regions at the center fold line, and a bag body and the holder are adhered together so that the center fold line and a lateral side of the bag body overlap each other, whereby the holder opens in a V-shape when in use. In addition, in order to ensure that the holder opens in a V-shape in this manner and the V-shape does not close while hot water is poured into the drip bag, a drip bag has been proposed that is provided with a foldable portion close to the fold line of the holder on the opening side of the bag body (Patent Document 1).
Similarly, a drip bag comprising a water permeable filterable sheet and a holder has been proposed. In case that hot water is poured into this drip bag, the shape of the opening is maintained wide by forming a fold line in the lateral direction intersecting the center fold line of the holder that is folded into right and left regions, as well as forming a cut line extending in the longitudinal direction at both the right and left ends of the fold line extending in the lateral direction, and then folding down the portion upwards from the fold line at the fold line extending in the lateral direction (Patent Document 2).    Patent Document 1: Japanese Patent Application Laid-Open No. 2004-242847    Patent Document 2: Japanese Patent Application Laid-Open No. 2002-238767